Antifriction composition



Patented July 22, 1941 UNITED s'rss ANTIFRICTION COMPOSITION Franz R. Hensel, Indianapolis, lind., assignor to l. R. Mallory & (70., Inc., Indianapolis, 11161., a

corporation of Delaware No Drawing. Application March 28, 1939, Serial No. 264,587

1 Claim.

This invention relates to metallic bodies, comprising compositions or mixtures which are frequently termed alloys, and are adapted for use as hearing materials, brushes and the like.

It is an object of the invention to provide an improved material, having excellent antifriction characteristics.

It is a further object of the invention to provide an improved material which is non-scoring.

Another object is that of providing an improved material as aforementioned, which will have good mechanical strength, high fatigue resistance and high corrosion resistance.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The present invention comprises a combination of elements, methods of manufacture and the product thereof, brought out and exemplifled in the disclosure hereinafter set forth, the scope of the invention being indicated in the appended claim.

While a preferred embodiment of the invention is described herein, it is contemplated that considerable variation may be made in the method of procedure and the combination of elements, without departing from the spirit of the invention.

According to the present invention, a metalliccomposition is provided, containing the essential ingredients in the following approximate proportions:

Per cent Metal taken from the 6th group of the periodic system, such as molybdenum and tungsten 40 .to '70 Metal of the iron group, such as iron,

cobalt and nickel .1 to 10 Soft low melting metal composed predominantly of metal selected from the group consisting of lead and tin Balance Within these composition ranges there are a number of specific compositions or mixtures, which have been found to be of particular im- Lead Substantially the bal me The preferred method of making compositions of the type described is to press the powders of metals from the sixth group of theperiodic system and the powders of metals taken from the iron group, together to a suitable density and pre-sintering such pressed bars. This sintering operation may be carried out in a reducing atmosphere, such a a hydrogen atmosphere. The temperatures may vary according to the composition and. will range anywhere from 700-1300 degrees C.

After such sintering operations have been completed then the lead or lead alloy is placed on the top of the pre-sintered piece and the impregnation process is carried out again in a reducing atmosphere, such as hydrogen-cracked ammonia, or other suitable gases. The temperature of impregnation may vary considerably, according to the pressed density of the presintered slug. The impregnation temperatures again may vary from 600 to 1100 or 1200 degrees C. In order to facilitate impregnation, small percentages of additional ingredients may be added, such as, for instance, silicon, phosphorus, copper or silver.

The resulting structure shows a very fine distribution of lead or lead alloy particles, surrounding the harder particles of the metals taken from the 6th group of the periodic system, and the metals from the iron group. Such a structure is ideally suitable for bearings, resulting in good antifriction and antiscoring properties.

Instead of. impregnating it is also possible to mix the ingredients together very intimately and press them into the desired shapes. After that, they may be sintered at a temperature at which lead is in the molten condition, causing the entire structure to be promptly bonded to gether. It is also possible to replace part of the lead by graphite, which still further improves combination of properties.

Scoring is directly connected with molecular cohesion when two solids are brought together and a more or less incipient welding of two metal surfaces in contact seems to take place.

Therefore, a very thin film of oil is necessary in all bearings of this type to prevent this metal to metal contact.

In bearings of the nature described, the danger of scoring is considerably decreased, because under increased heat, the lead or lead alloy might become molten, and act as a liquid lubricant.

It is believed that with the present invention a framework is formed of the refractory metal particles held together with the iron group metal 5- i I have found that instead of impregnating the refractory base with pure lead, lead alloys may be used, containing substantial quantities of tin, antimony and copper. In other words, instead of pure lead, lead alloys containing 84% lead,

5% tin, .5% copper, 10% antimony may be used, or the tin content may be even increased to the following proportions:

Per cent Tin 59.5 Lead 26 Copper 3 Antimony 10.5

These alloys of lead are known under the name of Babbitts and are all characterized by a low 3 melting point.

Other so-called soft metals may also be present, but in all cases, the melting point of these lead allows will be below 450 degrees C.

In testing bearings of the type described for hardness, it was found that the hardness will vary as a function of the temperature, and the following values were obtained on a composition containing about 70% tungsten, 25% iron, balance lead.

Brinoll hardness Materials of this type have been found particularly-useful in bearings for clocks, washing 5 machines,-vacuum sweepers, and the like. Ma-

terials of the type described have also been found to be useful as brushes on electric motors.

While the present invention as to its objects and advantages, has been described herein, as carried out in specific embodiments thereof, it is not desired to be limited thereby, but it is intended to cover the invention broadly, within thespirit and scope of the appended claim.

What is claimed is:

An electrical apparatus brush material formed of a heterogeneous metal composition formed of to 70% of particles of metal selected from the group consisting of molybdenum and tungsten, interspersed with .1 to 10% f metal se- 0 lected from the group consisting of iron, cobalt and nickel and the balance substantially all a soft low melting metal composed predominantly of metal selected from the group consisting of lead and tin, said low melting metal not exceeding of said composition, said low melting metal binding said composition together.

FRANZ R. HENSEL. 

